This is a discussion on How to choose wheel width? within the Suspension & Wheels forums, part of the Tech & Modifying & General Repairs category; Looking to get some new wheels for my 03 wagon... think I'm going for 17s. I'm definitely not looking for ...

How to choose wheel width?

Looking to get some new wheels for my 03 wagon... think I'm going for 17s. I'm definitely not looking for the stance look or for anything that is sacrificing performance. I'm also not looking to lower my car. I've been looking around and haven't really been able to find much info though on what the differences are between different sizes.

I'm currently thinking 17x7.5 or 8 -- I'm assuming more tire = more traction... but after a point I imagine it could actually hurt performance having too much rubber on the ground.

with a .5 inch difference. The tire choice will make the difference. If you want max performance, then those widths and that diameter are pretty much spot on for what you want. And offset, get as close to stock as possible. I think most wheels in those sizes will come in like 45-ish.

Wider wheel opens up wider tire widths. Wider tires will give you more contact patch, which will increase your ability to maintain traction in a corner. The additional weight will negatively impact acceleration. You need to figure out what's important to you. In general, a lightweight 17x8 wheel with a good 235-/245-series summer tire is a solid balance.

also Ive had the 17x8 +48 with 225 and now a 225 and a little lower than stock with no rubbing, the new wheels i just got are +35 so I'm assuming ill get a little rub. always best to stick to around stock offset but my inner dopeJDMswag gets the best of me sometimes.

I have 17x7.5 with a +48 offset and 225/45-17 tires on my '02. No rubbing.

That's the exact specs of a lot that I'm looking at. Great to know, thanks!

Originally Posted by wreckingball man

with a .5 inch difference. The tire choice will make the difference. If you want max performance, then those widths and that diameter are pretty much spot on for what you want. And offset, get as close to stock as possible. I think most wheels in those sizes will come in like 45-ish.

Gotcha, so you could theoretically run the same tire on either a 7.5" or a 8" rim. Didn't know that.

Originally Posted by EJ257

Wider wheel opens up wider tire widths. Wider tires will give you more contact patch, which will increase your ability to maintain traction in a corner. The additional weight will negatively impact acceleration. You need to figure out what's important to you. In general, a lightweight 17x8 wheel with a good 235-/245-series summer tire is a solid balance.

That's what I was figuring. This is pretty much exactly the info I was looking for... seems most all the info I could find about wheel/tire size has to do with OEM sizes, otherwise most people seem to know what they are talking about. I'd like something that fills up the wheel wells a bit more (for sexyness) and definitely something wider... stiffening up the swaybars on my car really made it apparent how small the stock tires are. At the same time though, I'm not looking to get into wide enough where I need to do bodywork to make them fit... or where my traction limits are way higher than I need - only a stage 2 bugeye, not like I need insane amounts of rubber on the road.

Originally Posted by Ruh Roh

^^^
i run a 17x8 with a 235/45 and its great. i think next tire ill buy a 245 because i like teh meat but a 235 is perfect.

also Ive had the 17x8 +48 with 225 and now a 225 and a little lower than stock with no rubbing, the new wheels i just got are +35 so I'm assuming ill get a little rub. always best to stick to around stock offset but my inner dopeJDMswag gets the best of me sometimes.

Sounds like the sweet spot, for sure. I'm definitely also going to get into more of a performance summer tire this time around vs all-seasons... I have Blizzaks I'll keep on the stock rims for the winter so might as well.

also Ive had the 17x8 +48 with 225 and now a 225 and a little lower than stock with no rubbing, the new wheels i just got are +35 so I'm assuming ill get a little rub. always best to stick to around stock offset but my inner dopeJDMswag gets the best of me sometimes.

Could you upload a side image of the car. Want to know what a +48 looks like.

Gotcha, so you could theoretically run the same tire on either a 7.5" or a 8" rim. Didn't know that.

Not exactly. There is a "sweet spot" of tires for a given wheel width. Too narrow of a tire, and it will be "stretched"; too wide of a tire and it will balloon out. Neither one of those is what you want; you want the sidewall to be pretty much perpendicular to the wheel surface it's being mounted on. With a 8" wheel, 245 is about the max you're going to be able to fit on there (some "XXX series" tires actually run a bit wider, so you may have to either go with a larger width wheel or drop down 10 for it to fit properly). A 7.5" wheel would not be able to support 245s, 235 is going to be about your max, assuming the condition I mentioned earlier isn't applicable.

Originally Posted by Monk_Knight

That's what I was figuring. This is pretty much exactly the info I was looking for... seems most all the info I could find about wheel/tire size has to do with OEM sizes, otherwise most people seem to know what they are talking about. I'd like something that fills up the wheel wells a bit more (for sexyness) and definitely something wider... stiffening up the swaybars on my car really made it apparent how small the stock tires are. At the same time though, I'm not looking to get into wide enough where I need to do bodywork to make them fit... or where my traction limits are way higher than I need - only a stage 2 bugeye, not like I need insane amounts of rubber on the road.

From this description, it sounds as though you're looking for a tire with a larger A/R to help fill up some wheel well gap. There is nothing wrong with that, but be aware that it will mean that you will be limited in what series tire you're able to run (due to rubbing), it will transmit less road feel, and it will likely cause your speedometer to be off more than a properly-sized profile tire (wider tire = lower A/R).

On the topic of speedometer...it is a calculation that factors in tire diameter (since the only change is tire size, we won't address all of the factors). If you choose to go with a higher A/R tire to fill up the wheel gap, the diameter of the tire is going to be larger. As a result, the revolutions/mile ratio will decrease, and your speedometer will read lower than your actual speed.

Not exactly. There is a "sweet spot" of tires for a given wheel width. Too narrow of a tire, and it will be "stretched"; too wide of a tire and it will balloon out. Neither one of those is what you want; you want the sidewall to be pretty much perpendicular to the wheel surface it's being mounted on. With a 8" wheel, 245 is about the max you're going to be able to fit on there (some "XXX series" tires actually run a bit wider, so you may have to either go with a larger width wheel or drop down 10 for it to fit properly). A 7.5" wheel would not be able to support 245s, 235 is going to be about your max, assuming the condition I mentioned earlier isn't applicable.

From this description, it sounds as though you're looking for a tire with a larger A/R to help fill up some wheel well gap. There is nothing wrong with that, but be aware that it will mean that you will be limited in what series tire you're able to run (due to rubbing), it will transmit less road feel, and it will likely cause your speedometer to be off more than a properly-sized profile tire (wider tire = lower A/R).

On the topic of speedometer...it is a calculation that factors in tire diameter (since the only change is tire size, we won't address all of the factors). If you choose to go with a higher A/R tire to fill up the wheel gap, the diameter of the tire is going to be larger. As a result, the revolutions/mile ratio will decrease, and your speedometer will read lower than your actual speed.

Gotcha. I hadn't considered that... I might just go for the equivalent size as stock then. I do like the idea of filling in the wheel well a bit (ideally without lowering the car) but I definitely am not looking to negatively impact any performance or drivability for it. Thanks for the info!

Wider wheel opens up wider tire widths. Wider tires will give you more contact patch, which will increase your ability to maintain traction in a corner. The additional weight will negatively impact acceleration. You need to figure out what's important to you. In general, a lightweight 17x8 wheel with a good 235-/245-series summer tire is a solid balance.

Of course this is all accurate, however there is also an upper limit to the amount of rubber that a suspension can keep in contact with the pavement. Different suspensions with different kingpin spacing and scrub radii will maintain different contact patches depending on the axle loading. Furthermore, McPherson struts have different dynamics compared to double-wishbone and multilink suspensions

For example, 13" wheel on a GD Subaru will not be able to maintain the full 13" contact patch over a use-able range of axle loading.

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